Methods and apparatus for manufacturing fiber-based microwavable food containers

ABSTRACT

Methods and apparatus for manufacturing a microwavable food container include: forming a wire mesh over a mold comprising a mirror image of the microwavable food container; immersing the wire mesh in a fiber-based slurry bath; drawing a vacuum across the wire mesh to cause fiber particles to accumulate at the wire mesh surface; and removing the wire mesh including the accumulated fiber particles from the slurry bath; wherein the slurry comprises a moisture barrier, an oil barrier, and a vapor barrier.

TECHNICAL FIELD

The present invention relates, generally, to ecologically sustainablemethods and apparatus for manufacturing containers and packagingmaterials and, more particularly, to the use of novel slurries for usein vacuum forming molded fiber products to replace plastics.

BACKGROUND

Pollution caused by single use plastic containers and packagingmaterials is epidemic, scarring the global landscape and threatening thehealth of ecosystems and the various life forms that inhabit them. Trashcomes into contact with waterways and oceans in the form of bits ofStyrofoam and expanded polystyrene (EPS) packaging, to-go containers,bottles, thin film bags and photo-degraded plastic pellets.

As this ocean trash accumulates it forms massive patches of highlyconcentrated plastic islands located at each of our oceans' gyres.Sunlight and waves cause floating plastics to break into increasinglysmaller particles, but they never completely disappear or biodegrade. Asingle plastic microbead can be one million times more toxic than thewater around it. Plastic particles act as sponges for waterbornecontaminants such as pesticides. Fish, turtles and even whales eatplastic objects, which can sicken or kill them. Smaller ocean animalsingest tiny plastic particles and pass them on to us when we eatseafood.

Sustainable solutions for reducing plastic pollution are gainingmomentum. However, continuing adoption requires these solutions to notonly be good for the environment, but also competitive with plasticsfrom both a performance and a cost standpoint. The present inventioninvolves replacing plastics with revolutionary technologies in moldedfiber without compromising product performance, within a competitivecost structure.

By way of brief background, molded paper pulp (molded fiber) has beenused since the 1930s to make containers, trays and other packages, butexperienced a decline in the 1970s after the introduction of plasticfoam packaging. Paper pulp can be produced from old newsprint,corrugated boxes and other plant fibers. Today, molded pulp packaging iswidely used for electronics, household goods, automotive parts andmedical products, and as an edge/corner protector or pallet tray forshipping electronic and other fragile components. Molds are made bymachining a metal tool in the shape of a mirror image of the finishedpackage. Holes are drilled through the tool and then a screen isattached to its surface. The vacuum is drawn through the holes while thescreen prevents the pulp from clogging the holes.

The two most common types of molded pulp are classified as Type 1 andType 2. Type 1 is commonly used for support packaging applications with3/16 inch (4.7 mm) to ½ inch (12.7 mm) walls. Type 1 molded pulpmanufacturing, also known as “dry” manufacturing, uses a fiber slurrymade from ground newsprint, kraft paper or other fibers dissolved inwater. A mold mounted on a platen is dipped or submerged in the slurryand a vacuum is applied to the generally convex backside. The vacuumpulls the slurry onto the mold to form the shape of the package. Whilestill under the vacuum, the mold is removed from the slurry tank,allowing the water to drain from the pulp. Air is then blown through thetool to eject the molded fiber piece. The part is typically deposited ona conveyor that moves through a drying oven.

Type 2 molded pulp manufacturing, also known as “wet” manufacturing, istypically used for packaging electronic equipment, cellular phones andhousehold items with containers that have 0.02 inch (0.5 mm) to 0.06inch (1.5 mm) walls. Type 2 molded pulp uses the same material andfollows the same basic process as Type 1 manufacturing up the pointwhere the vacuum pulls the slurry onto the mold. After this step, atransfer mold mates with the fiber package, moves the formed “wet part”to a hot press, and compresses and dries the fiber material to increasedensity and provide a smooth external surface finish. See, for example,http://www.stratasys.com/solutions/additive-manufacturing/tooling/molded-fiber;http://www.keiding.com/molded-fiber/manufacturing-process/; GrenideaTechnologies PTE Ltd. European Patent Publication Number EP 1492926 B1published Apr. 11, 2007 and entitled “Improved Molded FiberManufacturing”; andhttp://afpackaging.com/thermoformed-fiber-molded-pulp/. The entirecontents of all of the foregoing are hereby incorporated by thisreference.

Fiber-based packaging products are biodegradable, compostable and,unlike plastics, do not migrate into the ocean. However, presently knownfiber technologies are not well suited for use with meat and poultrycontainers, prepared food, produce, microwavable food containers, andlids for beverage containers such as hot coffee.

Methods and apparatus are thus needed which overcome the limitations ofthe prior art.

Various features and characteristics will also become apparent from thesubsequent detailed description and the appended claims, taken inconjunction with the accompanying drawings and this background section.

BRIEF SUMMARY

Various embodiments of the present invention relate to methods, chemicalformulae, and apparatus for manufacturing vacuum molded, fiber-basedpackaging and container products including, inter alia: i) meat,produce, horticulture, and utility containers embodying novel geometricfeatures which promote structural rigidity; ii) meat, produce,horticulture containers having embedded and/or topical moisture and/orvapor barriers; iii) vacuum tooling modified to re-direct spray nozzlesto increase the size of vent holes in produce and horticulturecontainers; iv) microwavable/oven-heated containers embodying embeddedand/or topical moisture, oil, and/or vapor barriers, and/or retentionaids to improve chemical bonding; v) meat containers embodying amoisture barrier which preserves structural rigidity over an extendedshelf life; vi) lids for hot beverage containers embodying a moistureand/or vapor barrier; and vii) vacuum tooling modified to include apiston for ejecting beverage lids having a negative draft from the mold.

It should be noted that the various inventions described herein, whileillustrated in the context of conventional slurry-based vacuum formprocesses, are not so limited. Those skilled in the art will appreciatethat the inventions described herein may contemplate any fiber-basedmanufacturing modality, including 3D printing techniques.

Various other embodiments, aspects, and features are described ingreater detail below.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Exemplary embodiments will hereinafter be described in conjunction withthe appended drawing figures, wherein like numerals denote likeelements, and:

FIG. 1 is a schematic block diagram of an exemplary vacuum formingprocess using a fiber-based slurry in accordance with variousembodiments;

FIG. 2 is a schematic block diagram of an exemplary closed loop slurrysystem for controlling the chemical composition of the slurry inaccordance with various embodiments;

FIG. 3 is a perspective view of an exemplary produce container depictinga rolled edge, overhanging skirt, and ribbed structural features forenhancing hoop strength in accordance with various embodiments;

FIG. 4 is an end view of the container shown in FIG. 3 in accordancewith various embodiments;

FIG. 5A is a perspective view of an exemplary produce containerincluding extended vent holes in accordance with various embodiments;

FIG. 5B is an end view of the container shown in FIG. 5A in accordancewith various embodiments;

FIGS. 6A-6C are alternate embodiments of food containers illustratingvarious shelf and rib features in accordance with various embodiments;

FIG. 7 is a perspective view of an exemplary rinsing tool includingspray nozzles configured to rinse pulp from vent hole inserts inaccordance with various embodiments;

FIG. 8 is a close up view of the spray nozzles shown in FIG. 7 inaccordance with various embodiments;

FIG. 9 is a perspective view of the excess fiber targeted for removal bythe spray nozzles shown in FIGS. 7 and 8 in accordance with variousembodiments;

FIG. 10 is a perspective view of an exemplary microwavable foodcontainer in accordance with various embodiments;

FIG. 11A is a perspective view of an exemplary meat container inaccordance with various embodiments;

FIG. 11B is an end view of the microwavable food container shown in FIG.11A in accordance with various embodiments;

FIG. 12 is an alternative embodiment of a shallow food tray illustratinga shelf having off-set ribs in accordance with various embodiments;

FIG. 13 is a perspective view of an exemplary lid for a liquid (e.g.,soup or a beverage such as coffee or soda) container in accordance withvarious embodiments;

FIG. 14 is a top view of the lid shown in FIG. 13 in accordance withvarious embodiments;

FIG. 15 is a side elevation view of the lid shown in FIGS. 13 and 14 inaccordance with various embodiments;

FIG. 16 is a perspective view of an exemplary mold for use inmanufacturing the lid shown in FIGS. 13-15 in accordance with variousembodiments;

FIG. 17 is a side elevation view of the mold of FIG. 16 shown in theretracted position in accordance with various embodiments;

FIG. 18 is a side elevation view of mold of FIG. 17 shown in theextended position in accordance with various embodiments; and

FIG. 19 is a perspective view of utility (non-food) container inaccordance with various embodiments.

DETAILED DESCRIPTION OF PREFERRED EXEMPLARY EMBODIMENTS

The following detailed description of the invention is merely exemplaryin nature and is not intended to limit the invention or the applicationand uses of the invention. Furthermore, there is no intention to bebound by any theory presented in the preceding background or thefollowing detailed description.

Various embodiments of the present invention relate to fiber-based orpulp-base products for use both within and outside of the food andbeverage industry. By way of non-limiting example, the presentdisclosure relates to particular chemical formulations of slurriesadapted to address the unique challenges facing the food industryincluding oil barriers, moisture barriers, water vapor barriers,strengthening additives, and/or retention aids, the absence of whichhave heretofore impeded fiber-based products from displacing single useplastic containers and components in the food industry. The presentdisclosure further contemplates fiber-based containers having geometricand structural features for enhanced rigidity. Coupling these featureswith novel chemistries enables fiber-based products to replace theirplastic counterparts in a wide variety of applications such as, forexample: frozen, refrigerated, and non-refrigerated foods; medical,pharmaceutical, and biological applications; microwavable foodcontainers; beverages; comestible and non-comestible liquids; substanceswhich liberate water, oil, and/or water vapor during storage, shipment,and preparation (e.g., cooking); horticultural applications includingconsumable and landscaping/gardening plants, flowers, herbs, shrubs, andtrees; chemical storage and dispensing apparatus (e.g., paint trays);produce (including human and animal foodstuffs such as fruits andvegetables); salads; prepared foods; packaging for meat, poultry, andfish; lids; cups; bottles; guides and separators for processing anddisplaying the foregoing; edge and corner pieces for packing, storing,and shipping electronics, mirrors, fine art, and other fragilecomponents; buckets; tubes; industrial, automotive, marine, aerospaceand military components such as gaskets, spacers, seals, cushions, andthe like; and associated molds, wire mesh forms, recipes, processes,chemical formulae, tooling, slurry distribution, chemical monitoring,chemical infusion, and related systems, apparatus, methods, andtechniques for manufacturing the foregoing components.

Referring now to FIG. 1, an exemplary vacuum forming system and process100 using a fiber-based slurry includes a first stage 101 in which mold(not shown for clarity) in the form of a mirror image of the product tobe manufactured is envelop in a thin wire mesh form 102 to match thecontour of the mold. A supply 104 of a fiber-based slurry 104 is inputat a pressure (P1) 106 (typically ambient pressure). By maintaining alower pressure (P2) 108 inside the mold, the slurry is drawn through themesh form, trapping fiber particles in the shape of the mold, whileevacuating excess slurry no for recirculation back into the system.

With continued reference to FIG. 1, a second stage 103 involvesaccumulating a fiber layer 130 around the wire mesh in the shape of themold. When the layer 130 reaches a desired thickness, the mold enters athird stage 105 for either wet or dry curing. In a wet curing process,the formed part is transferred to a heated press (not shown) and thelayer 130 is compressed and dried to a desired thickness, therebyyielding a smooth external surface finish for the finished part. In adry curing process, heated air is passed directly over the layer 130 toremove moisture therefrom, resulting in a more textured finish much likea conventional egg carton.

In accordance with various embodiments the vacuum mold process isoperated as a closed loop system, in that the unused slurry isre-circulated back into the bath where the product is formed. As such,some of the chemical additives (discussed in more detail below) areabsorbed into the individual fibers, and some of the additive remains inthe water-based solution. During vacuum formation, only the fibers(which have absorbed some of the additives) are trapped into the form,while the remaining additives are re-circulated back into the tank.Consequently, only the additives captured in the formed part must bereplenished, as the remaining additives are re-circulated with theslurry in solution. As described below, the system maintains a steadystate chemistry within the vacuum tank at predetermined volumetricratios of the constituent components comprising the slurry.

Referring now to FIG. 2, is a closed loop slurry system 200 forcontrolling the chemical composition of the slurry. In the illustratedembodiment a tank 202 is filled with a fiber-based slurry 204 having aparticular desired chemistry, whereupon a vacuum mold 206 is immersedinto the slurry bath to form a molded part. After the molded part isformed to a desired thickness, the mold 206 is removed for subsequentprocessing 208 (e.g., forming, heating, drying, top coating, and thelike).

In a typical wet press process, the Hot Press Temperature Range isaround 150-250 degree C., with a Hot Press Pressure Range around 140-170kg/cm². The final product density should be around 0.5-1.5 g/cm³, andmost likely around 0.9-1.1 g/cm³. Final product thickness is about0.3-1.5 mm, and preferably about 0.5-0.8 mm.

With continued reference to FIG. 2, a fiber-based slurry comprising pulpand water is input into the tank 202 at a slurry input 210. In variousembodiments, a grinder may be used to grind the pulp fiber to createadditional bonding sites. One or more additional components or chemicaladditives may be supplied at respective inputs 212-214. The slurry maybe re-circulated using a closed loop conduit 218, adding additional pulpand/or water as needed. To maintain a steady state balance of thedesired chemical additives, a sampling module 216 is configured tomeasure or otherwise monitor the constituent components of the slurry,and dynamically or periodically adjust the respective additive levels bycontrolling respective inputs 212-214. Typically the slurryconcentration is around 0.1-1%, most ideally around 0.3-0.4%. In oneembodiment, the various chemical constituents are maintained at apredetermined desired percent by volume; alternatively, the chemistrymay be maintained based on percent by weight or any other desiredcontrol modality.

The pulp fiber used in 202 can also be mechanically grinded to improvefiber-to-fiber bonding and improve bonding of chemicals to the fiber. Inthis way the slurry undergoes a refining process which changes thefreeness, or drainage rate, of fiber materials. Refining physicallymodifies fibers to fibrillate and make them more flexible to achievebetter bonding. Also, the refining process can increases tensile andburst strength of the final product. Freeness, in various embodiments,is related to the surface conditions and swelling of the fibers.Freeness (csf) is suitably within the range of 200-700, and preferablyabout 220-250 for many of the processes and products described herein.

The chemical formulae (sometimes referred to herein as “chemistries”)and product configurations for various fiber-based packages andcontainers, as well as their methods for manufacture, will now bedescribed in conjunction with FIGS. 3-19.

Produce Containers

FIG. 3 is a perspective view of an exemplary produce container (e.g.,mushroom till) 300 depicting a rolled edge 302, overhanging skirt 304,and various structural features including side panels exhibiting anoutward bow, side ribs 306 and bottom ribs 308 for enhancing hoopstrength. In this context, the term hoop strength refers to a measure ofthe applied lateral force along opposing vectors 310 versus theresulting deflection. Although the initial hoop strength of a containeris primarily a function of geometry, hoop strength tends to degrade asthe container absorbs moisture leached or otherwise liberated from itscontents (e.g., mushrooms). The present inventor has determined thatcoupling various geometric features with slurry chemistries optimizedfor various applications can sustain hoop strength over extended shelftimes. That is, by incorporating a moisture repellant barrier into theslurry (and/or applying a moisture repellant surface coating), the hoopstrength may be maintained for a longer period of time even as thecontainer contents bleed moisture.

FIG. 4 is an end view of a container 400 generally analogous to thecontainer shown in FIG. 3, and illustrates a width dimension 402, aheight dimension 404, and a skirt length 408 in the range of 0.1 to 5millimeters, and preferably about 1.5 mm. in the illustrated embodiment,the skirt extends downwardly; alternatively, the skirt may extend at anoblique or obtuse angle relative to a vertical plane. Width and heightdimensions 402, 404 may be any desired values, for example in the rangeof 20 to 400 mm, and preferably about 60 to 200 mm.

As briefly mentioned above, the various slurries used to vacuum moldcontainers according to the present invention comprises a fiber basemixture of pulp and water, with added chemical components to impartdesired performance characteristics tuned to each particular productapplication. The base fiber may include any one or combination of atleast the following materials: softwood (SW), bagasse, bamboo, oldcorrugated containers (OCC), and newsprint (NP). Alternatively, the basefiber may be selected in accordance with the following resources, theentire contents of which are hereby incorporated by this reference:“Lignocellulosic Fibers and Wood Handbook: Renewable Materials forToday's Environment,” edited by Mohamed Naceur Belgacem and AntonioPizzi (Copyright 2016 by Scrivener Publishing, LLC) and available athttps://books.google.com/books?id=jTL8CwAAQBAJ&printsec=frontcover#v-onepage&q&f=false;“Efficient Use of Flourescent Whitening Agents and Shading Colorants inthe Production of White Paper and Board” by Liisa Ohlsson and RobertFedere, Published Oct. 8, 2002 in the African Pulp and Paper Week andavailable athttp://www.tappsa.co.za/archive/APPW2002/Title/Efficient_use_of_fluorescent_w/efficient_use_of_fluorescent_w.html;Cellulosic Pulps, Fibres and Materials: Cellucon '98 Proceedings, editedby J F Kennedy, G O Phillips, P A Williams, copyright 200 by WoodheadPublishing Ltd. and available athttps://books.google.com/books?id=xO2iAgAAOBAJ&printsec=frontcover#v=onepage&q&f=faise;and U.S. Pat. No. 5,169,497 A entitled “Application of Enzymes andFlocculants for Enhancing the Freeness of Paper Making Pulp” issued Dec.8, 1992.

For vacuum molded produce containers manufactured using either a wet ordry press, a fiber base of OCC and NP may be used, where the OCCcomponent is between 50%-100%, and preferably about 70% OCC and 30% NP,with an added moisture/water repellant in the range of 1%-10% by weight,and preferably about 1.5%-4%, and most preferably about 4%. In apreferred embodiment, the moisture/water barrier may comprisealkylketene dimer (AKD) (for example, AKD 80) and/or long chaindiketenes, available from FOBCHEM athttp://www.fobchem.com/html_products/Alkyl-Ketene-Dimer%EF%BC%88AKD-WAX%EF%BC%89.html#.VozozvkrKUk;and Yanzhou Tiancheng Chemical Co., Ltd. athttp://www.yztianchengchem.com/en/index.php?m=content&c=index&a=show&catid=38&id=124&gclid=CPbn65aUg80CFRCOaQodoJUGRg.

In order to yield specific colors for molded pulp products, cationic dyeor fiber reactive dye may be added to the pulp. Fiber reactive dyes,such as Procion MX, bond with the fiber at a molecular level, becomingchemically part of the fabric. Also, adding salt, soda ash and/orincrease pulp temperature will help the absorbed dye to be furtherlylocked in the fabric to prevent color bleeding and enhance the colordepth.

To enhance structural rigidity, a starch component may be added to theslurry, for example, liquid starches available commercially as Topcat®L98 cationic additive, Hercobond, and Topcat® L95 cationic additive(available from Penford Products Co. of Cedar Rapids, Iowa).Alternatively, the liquid starch can also be combined with low chargeliquid cationic starches such as those available as Penbond® cationicadditive and PAF 9137 BR cationic additive (also available from PenfordProducts Co., Cedar Rapids, Iowa).

For dry press processes, Topcat L95 may be added as a percent by weightin the range of 0.5%-10%, and preferably about 1%-7%, and particularlyfor products which need maintain strength in a high moisture environmentmost preferably about 6.5%; otherwise, most preferably about 1.5-2.0%.For wet press processes, dry strength additives such as Topcat L95 orHercobond which are made from modified polyamines that form bothhydrogen and ionic bonds with fibers and fines. Dry strength additiveshelp to increase dry strength, as well as drainage and retention, andare also effective in fixing anions, hydrophobes and sizing agents intofiber products. Those additives may be added as a percent by weight inthe range of 0.5%-10%, and preferably about 1%-6%, and most preferablyabout 3.5%. In addition, both wet and dry processes may benefit from theaddition of wet strength additives, for example solutions formulatedwith polyamide-epichlorohydrin (PAE) resin such as Kymene 577 or similarcomponent available from Ashland Specialty Chemical Products athttp://www.ashland.com/products. In a preferred embodiment, Kymene 577may be added in a percent by volume range of 0.5%-10%, and preferablyabout 1%-4%, and most preferably about 2% or approximately equal amountwith dosing of dry strength additives. Kymene 577 is of the class ofpolycationic materials containing an average of two or more amino and/orquaternary ammonium salt groups per molecule. Such amino groups tend toprotonate in acidic solutions to produce cationic species. Otherexamples of polycationic materials include polymers derived from themodification with epichlorohydrin of amino containing polyamides such asthose prepared from the condensation adipic acid and dimethylenetriamine, available commercially as Hercosett 57 from Hercules andCatalyst 3774 from Ciba-Geigy.

In some packaging applications it is desired to allow air to flowthrough the container, for example, to facilitate ripening or avoidspoliation of the contents (e.g. tomatoes). However, conventional vacuumtooling typically rinses excess fiber from the mold using a downwardlydirected water spry, thereby limiting the size of the resulting ventholes in the finished produce. The present inventor has determined thatre-directing the spray facilitates greater fiber removal during therinse cycle, producing a larger vent hole in the finished product for agiven mold configuration.

More particularly, FIG. 5A is a perspective view of an exemplary producecontainer 500 including extended relief holes 502. FIG. 5B is an endview of a container 504 illustrating extended vent holes 506. In thiscontext, the term “extended vent holes” refers to holes made using themodified tooling shown in FIGS. 9-7, discussed below.

Referring now to FIGS. 6A-6C, various combinations of geometric featuresmay be employed to enhance the structural rigidity/integrity of foodcontainers. By way of non-limiting example, one or more horizontallyextending shelfs 602, 604 may be disposed between an upper region and alower region of a side wall. For side walls containing a single shelf,the shelf may be disposed in the range of 30%-50% of the wall heightfrom the top of the tray, and preferably about 35%. The shelf may becreated by indenting the side panel and/or varying the draft angle. Forexample, in the embodiment shown in FIG. 6C, a lower region 606 exhibitsa draft angle in the range of about 4-6° (and preferably about 5°),while an upper region 608 exhibits a draft angle in the range of about6-8° (and preferably about 7°).

With continued reference to FIGS. 6A-6C, various rib configurations 610may be disposed along the bottom and up the side panels of foodcontainers. Ribs may be configured to terminate at a shelf, above theshelf (e.g., in the upper region of a side wall, for example 25% of thedistance down from the top edge), below the shelf (e.g., in the lowerregion of a side wall, for example 25% of the distance down from theshelf), or at the top edge of the side wall. As shown in FIG. 6C, ribs612 may extend from the bottom of the container upwardly and terminateat the shelf, whereupon subsequent ribs 614 may be off set from the ribs612 and extend upwardly from the shelf. The ribs may terminate in arounded, squared, or other desired geometrical shape or configuration.

Vent Hole Tooling

FIG. 7 is a directional water impingement cleaning system 700 includinga plurality of re-directed spray nozzles 704 configured to rinse excesspulp from vent hole inserts 706. More particularly, a mold (not shown)is covered by a wire mesh 708, the mold including the inserts whichcorrespond to vent holes in the finished product. A supply conduit 702distributes rinse water to a manifold 711 which includes a plurality ofspray nozzles, each configured to direct rinse water to remove excessfiber proximate the inserts.

With momentary reference to FIG. 8, a close up view 800 of a section ofa manifold 811 depicts a spray nozzle 802 configured to direct rinsewater proximate a corresponding insert 706. In this way, a greaterextent of the residual fibers surrounding the inserts is removed,resulting in extended vent holes in the finished produce vis-à-vispresently known systems which simply rinse the mold with water sprayedfrom above. Importantly, the extended vent holes may be realized withouthaving to adjust the underlying mold or inserts.

As seen in FIG. 9, the excess fiber 900 targeted for removal by theimproved spray nozzles of the present invention provides extended ventholes using existing molds and presently known inserts.

Microwavable Containers

Building on knowledge obtained from the development of theaforementioned produce containers, the present inventor has determinedthat molded fiber containers can be rendered suitable as single use foodcontainers suitable for use in microwave, convection, and conventionalovens by optimizing the slurry chemistry. In particular, the slurrychemistry should advantageously accommodate one or more of the followingthree performance metrics: i) moisture barrier; ii) oil barrier; andiii) water vapor (condensation) barrier to avoid condensate due toplacing the hot container on a surface having a lower temperature thanthe container. In this context, the extent to which water vaporpermeates the container is related to the porosity of the container,which the present invention seeks to reduce. That is, even if thecontainer is effectively impermeable to oil and water, it maynonetheless compromise the user experience if water vapor permeates thecontainer, particularly if the water vapor condenses on a cold surface,leaving behind a moisture ring. The present inventor has furtherdetermined that the condensate problem is uniquely pronounced infiber-based applications because water vapor typically does not permeatea plastic barrier.

Accordingly, for microwavable containers the present inventioncontemplates a fiber or pulp-based slurry including a water barrier, oilbarrier, and water vapor barrier, and optional strengthening and/orretention aids. In an embodiment, a fiber base of softwood (SW)/bagasseat a ratio in the range of about 10%-90%, and preferably about 7:3 maybe used. As a water/moisture barrier, AKD may be used in the range ofabout 0.5%-10%, and preferably about 1.5%-4%, and most preferably about3.5%. As an oil barrier, the grease and oil repellent additives areusually water based emulsions of fluorine containing compositions offluorocarbon resin or other fluorine-containing polymers such as UNIDYNETG 8111 or UNIDYNE TG-8731 available from Daikin or World of Chemicalsathttp://www.worldofchemicals.com/chemicals/chemical-properties/unidyne-tg-8111.html.The oil barrier component of the slurry (or topical coat) may comprise,as a percentage by weight, in the range of 0.5%-10%, and preferablyabout 1%-4%, and most preferably about 2.5%. As a retention aid, anorganic compound such as Nalco 7527 available from the Nalco Company ofNaperville, Ill. May be employed in the range of 0.1%-1% by volume, andpreferably about 0.3%. Finally, to strengthen the finished product, adry strength additive such as an inorganic salt (e.g., Hercobond 6950available athttp://solenis.com/en/industries/tissue-towel/innovations/hercobond-dry-strength-additives/;see also http://www.sfm.state.or.us/CR2K_SubDB/MSDS/HERCOBOND_6950.PDF)may be employed in the range of 0.5%-10% by weight, and preferably about1.5%-5%, and most preferably about 4%.

As mentioned, vapor barrier performance is directly impacted by porosityof the fiber tray. Reducing the porosity of the fiber tray and, hence,improving vapor barrier performance can be achieved using at least twoapproaches. One is by improving freeness of the tray material bygrinding the fibers. The second way is by topical spray coating using,for example, Daikin S2066, which is a water based long chainFlourione-containing polymer. Spray coating may be implemented using inthe range of about 0.1%-3% by weight, and preferably about 0.2%-1.5%,and most preferably about 1%.

Referring now to FIG. 10, an exemplary microwavable food container 1000depicts two compartments; alternatively, the container may comprise anydesired shape (e.g., a round bowl, elliptical, rectangular, or thelike). As stated above, the various water, oil, and vapor barriers maybe embedded into the slurry, applied topically as a spray on coating, orboth.

Meat Containers

Presently known meat trays, such as those used for he display ofpoultry, beef, pork, and seafood in grocery stores, are typically madeof plastic based materials such as polystyrene and Styrofoam, primarilybecause of their superior moisture barrier properties. The presentinventor has determined that variations of the foregoing chemistriesused for microwavable containers may be adapted for use in meat trays,particularly with respect to the moisture barrier (oil and porositybarriers are typically not as important in a meat tray as they are in amicrowave container).

Accordingly, for meat containers the present invention contemplates afiber or pulp-based slurry including a water barrier and an optional oilbarrier. In an embodiment, a fiber base of softwood (SW)/bagasse and/orbamboo/bagasse at a ratio in the range of about 10%-90%, and preferablyabout 7:3 may be used. As a moisture/water barrier, AKD may be used inthe range of about 0.5%-10%, and preferably about 1%-4%, and mostpreferably about 4%. As an oil barrier, a water based emulsion may beemployed such as UNIDYNE TG 8111 or UNIDYNE TG-8731. The oil barriercomponent of the slurry (or topical coat) may comprise, as a percentageby weight, in the range of 0.5%-10%, and preferably about 1%-4%, andmost preferably about 1.5%. Finally, to strengthen the finished product,a dry strength additive such as Hercobond 6950 may be employed in therange of 0.5%-10% by weight, and preferably about 1.5%-4%, and mostpreferably about 4%.

As discussed above in connection with the produce containers, the slurrychemistry may be combined with structural features to provide prolongedrigidity over time by preventing moisture/water from penetrating intothe tray.

FIG. 11A is a perspective view of an exemplary meat container 1100, andFIG. 11B is an end view of the meat container shown in FIG. 11Aincluding sidewall ribs 1102 and bottom ribs 1104.

FIG. 12 is a perspective view of an exemplary shallow meat container1200 including a rib 1202 extending along the bottom and upwardly alongthe side wall, terminating at a shelf 1204. A second rib 1206, offsetfrom the first rib 1202, extends upwardly from the shelf.

Beverage Lids

Although fiber and pulp based paper cups are widely known, the beverageindustry still needs a sustainable fiber-based lid solution. Asignificant impediment to the widespread adoption of fiber-based lidssurrounds the ability to incorporate a zero or negative draft into thelid, in a manner which allows it to be conveniently removed from themold. In addition, the fiber-based chemistry must be adapted to providean adequate moisture/water barrier so that the rigidity of the lid isnot compromised in the presence of liquid. The methods, chemicalformulae, and tooling contemplated by the present invention addressesboth of these issues in a manner heretofore not address by the priorart.

In particular, the chemistry for lids is similar to meat trays andmicrowave bowls discussed above. Specifically, for beverage containerlids the present invention contemplates a fiber or pulp-based slurryincluding a water/moisture barrier and an optional retention aid. In anembodiment, a fiber base of softwood (SW)/bagasse and/or bamboo/bagasseat a ratio in the range of about 10%-90%, and preferably about 7:3 maybe used. As a moisture/water barrier, AKD may be used in the range ofabout 0.5%-10%, and preferably about 1%-4%, and most preferably about4%. Rigidity may be enhanced by Hercobond 6950 in the range of 0.5%-10%by weight, and preferably about 1%-4%, and most preferably about 2% or,alternatively, an equal amount as dry strength additives used in thesystem. Kymene may also be added in the range of 0.5%-10%, andpreferably about 1%-4%, and most preferably about 3%. In variousembodiments, the Hercobond and/or the Kymene (or functionally analogousadditives) may be added to the slurry before addition of the AKD.

Referring now to FIG. 13, an exemplary lid 1300 includes an inclinedplatform 1302 surrounded by a retaining wall 1303 designed to urgeliquid which leaves the inside of the container toward a sip hole 1304.A small venting aperture 1310 may be disposed on the platform 1302. Acrown 1306 defines a volumetric space between the top of the cup (notshown) and the platform 1302, and a lock ring 1308 is configured tosecurely snap around the top of the cup. FIG. 14 is a top view of thelid shown in FIG. 13, including a platform 1402 venting aperture 1410,and sip hole 1404 for comparison.

FIG. 15 is a side elevation view of a lid 1500, highlighting a negativedraft 1522 associated with the lock ring. Conventional wisdom suggeststhat vacuum molded products may not embody zero or negative draftfeatures, because conventional vacuum mold tooling does not allow thefinished part to be removed from the tool, inasmuch as the negativedraft feature would “lock” the part to the tool in much the same way asthe finished part “locks” itself to its mating component (here, thebeverage cup). To overcome this limitation, the present inventioncontemplates a vacuum mold tool which removes the lid from the mold,notwithstanding the presence of the zero or negative draft lockingfeature, as described in greater detail below in conjunction with FIGS.13-18.

Lid Tooling

A tool for making a fiber-based lid having a zero or negative draftcomprises a retractable piston having a shape which generally to amirror image of the lid, and which is configured to extend to unlock thefinished lid from that part of the mold which the lid locks to.

Referring now to FIG. 16, is a perspective view of an exemplary moldassembly for use in manufacturing the lid shown in FIGS. 13-15 inaccordance with various embodiments. More particularly, a mold assembly1600 includes a mold block 1620 supporting a lock ring mold portion 1608(corresponding to the lock ring 1308 of FIG. 13), a retractable pistonassembly comprising a crown portion 1630 having an inclined platform1602 (corresponding to the inclined platform 1302 of FIG. 13), and ashaft portion 1640. In operation, a lid is vacuumed formed in a slurrybath (not shown) and then transferred onto the hot press shown in FIG.16. A female portion of the lid tool then compresses the wet vacuumedformed lid using heat and pressure.

FIG. 17 is a side elevation view of the mold of FIG. 16 shown in theretracted position. In particular, the crown portion 1706 of the pistonis adjacent the lock ring portion 1708 of the mold block 1720 when thepiston is in the retracted position shown in FIG. 17. When the lid isformed when pressed, the negative draft portion 1522 of the lid (seeFIG. 15) locks around the corresponding negative draft portion 1722 ofthe lock ring portion 1708 of the mold. In order to remove the finishedpart from the mold, the piston is extended upwardly, forcing the lockring of the lid to momentarily expand and unlock from the mold.

FIG. 18 shows the piston in the extended position. In particular, theshaft 1840 forces the crown portion 1830 away from the lock ring portion1808, unlocking the lid from the negative draft feature 1822 of themold. In an embodiment, the piston is extended pneumatically, andallowed to retract by its own weight once the high pressure air isreleased.

Utility and Shipping Containers

FIG. 19 is a perspective view of utility (non-food) container 1900including sidewall ribs 1902 and a perimeter lip 1904 in accordance withvarious embodiments. Depending on the nature of the contained material,any one or combination of the aforementioned chemistries may be used inthe construction of the container. For example, if the contained liquidincludes a water component, a suitable moisture/water barrier may beemployed; if the contained material includes an oil component, asuitable oil barrier may be employed, and so on.

While the present invention has been described in the context of theforegoing embodiments, it will be appreciated that the invention is notso limited. For example, the various geometric features and chemistriesmay be adjusted to accommodate additional applications based on theteachings of the present invention.

A method is thus provided for manufacturing a produce container. Themethod includes: forming a wire mesh over a mold comprising a mirrorimage of the produce container; immersing the wire mesh in a fiber-basedslurry bath; drawing a vacuum across the wire mesh to cause fiberparticles to accumulate at the wire mesh surface; and removing the wiremesh from the slurry bath; wherein the slurry comprises a moisture/waterbarrier component in the range of 1.5%-4% by weight.

In an embodiment the slurry comprises a moisture barrier component inthe range of about 4%.

In an embodiment the moisture barrier component comprises alkyltenedimer (AKD).

In an embodiment the moisture barrier component comprises alkyltenedimer (AKD) 80.

In an embodiment the slurry comprises a fiber base of OCC/NP at a ratioin the range of 0.5/9.5.

In an embodiment the slurry further comprises a dry strength componentin the range of 1%-7% by weight.

In an embodiment the starch component comprises a cationic liquidstarch.

In an embodiment the slurry further comprises a wet strength componentsuch as Kymene (e.g., Kymene 577) in the range of 1%-4% by weight.

In an embodiment the mold comprises a rolled edge including a verticallydescending skirt.

In an embodiment the moisture/water barrier comprises AKD in the rangeof about 4%, wherein the AKD may be added to the pulp slurry as adiluted solution (e.g., 1:10 ADK:Water); the slurry comprises a cationicliquid starch component in the range of 1%-7%; and the mold comprises arolled edge including a vertically descending skirt, at least one bottomrib, and at least one sidewall rib.

A produce container manufactured according to the foregoing methods isalso provided.

In a vacuum mold assembly of the type including a wire mesh surroundinga mold form having a substantially vertical insert configured to providea vent hole in a finished container, a directional rinse assembly isprovided. The directional rinse assembly includes: a water supplyconduit; a manifold connected to the water supply conduit; and a spraynozzle connected to the manifold and configured to direct a spray ofwater at the insert along a vector having a horizontal component.

In an embodiment the mold includes a plurality of substantially verticalinserts, and the directional rinse assembly further includes a pluralityof spray nozzles, each configured to direct a spray of water atrespective inserts along respective vectors each having a horizontalcomponent.

A method is also provided for manufacturing a zero or nearly zeroporosity food container. This method includes a wet press procedure asthe first step, followed by an extra surface coating procedure forapplying a thin layer of water based long chain fluorine-containingpolymers such as Daikin S 2066, in the range of about 0.5%-6% by weight,and preferably about 1%-5%, and most preferably about 4%.

A method is also provided for manufacturing a microwavable and/or ovenworthy food container. The method includes: forming a wire mesh over amold comprising a mirror image of the microwavable food container;immersing the wire mesh in a fiber-based slurry bath; drawing a vacuumacross the wire mesh to cause fiber particles to accumulate at the wiremesh surface; and removing the wire mesh from the slurry bath; whereinthe slurry comprises a moisture barrier component in the range of0.5%-10% by weight, an oil barrier in the range of 0.5%-10% by weight,and a retention aid in the range of 0.05%-5% by weight.

In an embodiment the moisture/water barrier component is in the range ofabout 1.5%-4%, the oil barrier is in the range of about 1%-4%, and theretention aid is in the range of about 0.1%-0.5%.

In an embodiment the moisture barrier component comprises alkyltenedimer (AKD).

In an embodiment the moisture barrier component comprises alkyltenedimer (AKD) 79.

In an embodiment the slurry comprises a fiber base of SW/bagasse at aratio in the range of 0.5/9.5.

In an embodiment the slurry further comprises a rigidity component inthe range of 1%-5% by weight.

In an embodiment the rigidity component comprises a dry inorganic salt.

In an embodiment the oil barrier comprises a water based emulsion.

In an embodiment the oil barrier comprises TG 8111.

In an embodiment the retention aid comprises an organic compound.

In an embodiment the retention aid comprises Nalco 7527.

In an embodiment the moisture/water barrier comprises AKD in the rangeof about 4%; the slurry comprises bagasse and a dry inorganic salt; theoil barrier comprises a water based emulsion; and the vapor barriercomprises an organic compound.

A microwavable container manufactured according to the foregoing methodsis also provided.

A method of manufacturing a meat tray is provided, the method including:forming a wire mesh over a mold comprising a mirror image of the meattray; immersing the wire mesh in a fiber-based slurry bath; drawing avacuum across the wire mesh to cause fiber particles to accumulate atthe wire mesh surface; and removing the wire mesh from the slurry bath;wherein the slurry comprises a moisture/water barrier component in therange of 0.5%-10% by weight and an oil barrier in the range of 0.5%-10%by weight.

In an embodiment the moisture/water barrier component is in the range ofabout 1%-4% and the oil barrier is in the range of about 1%-4.

In an embodiment the moisture barrier component comprises alkyltenedimer (AKD).

In an embodiment the moisture barrier component comprises alkyltenedimer (AKD) 79.

In an embodiment the slurry comprises a fiber base of SW/bagasse at aratio in the range of 1/9.

In an embodiment the slurry includes a rigidity component in the rangeof 1.5%-4% by weight.

In an embodiment the rigidity component comprises a dry inorganic salt.

In an embodiment the oil barrier comprises a water based emulsion.

In an embodiment the oil barrier comprises TG 8111 in the range of about1.5% by weight; the TG8111 may be added to the pulp slurry as a dilutedsolution (e.g., 1:5, TG8111: Water).

In an embodiment the moisture/water barrier comprises AKD in the rangeof about 4%; the slurry comprises bagasse and a dry inorganic salt; andthe oil barrier comprises a water based emulsion.

A meat tray manufactured according to the foregoing methods is alsoprovided.

In an embodiment the meat tray includes at least one sidewall rib and atleast one bottom rib.

A method of manufacturing a lid for a beverage container is alsoprovided. The method includes: forming a wire mesh over a moldcomprising a mirror image of the lid; immersing the wire mesh in afiber-based slurry bath; drawing a vacuum across the wire mesh to causefiber particles to accumulate at the wire mesh surface; and removing thewire mesh from the slurry bath; wherein the slurry comprises amoisture/water barrier component in the range of 0.5%-10% by weight, arigidity component in the range of 1%-4% by weight, and a polycationiccomponent in the range of about 1%-4%.

In an embodiment the moisture/water barrier component is in the range ofabout 1%-4% and the oil barrier is in the range of about 1%-4.

In an embodiment the moisture barrier component comprises alkyltenedimer (AKD).

In an embodiment the moisture barrier component comprises alkyltenedimer (AKD) 80.

In an embodiment the slurry comprises a fiber base of SW/bagasse at aratio in the range of 1/9.

In an embodiment the slurry further comprises a rigidity component inthe range of 1.0%-4% by weight.

In an embodiment the rigidity component comprises a dry inorganic salt.

In an embodiment the moisture/water barrier comprises AKD in the rangeof about 4%; the slurry comprises bagasse and a dry inorganic salt; andthe slurry comprises a polycationic material in the range of about 1%-4%by weight.

A lid manufactured according to the foregoing methods is also provided.

In an embodiment the lid further includes a lock ring having anon-positive draft.

A vacuum tool is also provided for manufacturing a fiber-based beveragelid having a crown and a lock ring including a negative draft. The toolincludes: a mold block supporting a lock ring mold portion correspondingto the lid lock ring; a retractable piston assembly comprising a crownmold portion corresponding to the lid crown and a piston shaft; and apneumatic actuator configured to extend the piston shaft to therebyremove the lid lock ring from the lock ring mold portion.

In an embodiment the vacuum tool further includes a wire mesh removablysurrounding the crown mold portion and the lock ring mold portion.

A shipping container kit is also provided for a flat screen TV. The kitincludes: a top cover; a screen protector; four corrugated pulp cornerpieces configured to fit over respective corresponding corners of theflat screen TV; a bottom tray configured to nest with the top cover; anda pallet strap configured to secure the TV, screen protector, corrugatedpulp corner pieces within the nested top cover and bottom tray.

As used herein, the word “exemplary” means “serving as an example,instance, or illustration.” Any implementation described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other implementations, nor is it intended to beconstrued as a model that must be literally duplicated.

While the foregoing detailed description will provide those skilled inthe art with a convenient road map for implementing various embodimentsof the invention, it should be appreciated that the particularembodiments described above are only examples, and are not intended tolimit the scope, applicability, or configuration of the invention in anyway. To the contrary, various changes may be made in the function andarrangement of elements described without departing from the scope ofthe invention.

The invention claimed is:
 1. A slurry for use in vacuum forming afiber-based microwavable food container, the slurry comprising: anaqueous pulp mixture comprising fibers ground from at least one of oldcorrugated containers (OCC) and newsprint (NP); a moisture barriercomponent in the range of 0.5%-10% of the slurry weight; an oil barriercomponent in the range of 0.5%-10% of the slurry weight, where the oilbarrier component is different from the moisture barrier component; anda rigidity component in the range of 1%-5% of the slurry weight.
 2. Theslurry of claim 1, further comprising a retention aid.
 3. The slurry ofclaim 2, wherein the moisture barrier is in the range of about 1.5%-4%,the oil barrier is in the range of about 1%-4%, and the retention aid isin the range of about 0.1%-0.5%.
 4. The slurry of claim 3, wherein themoisture barrier comprises alkyltene dimer (AKD).
 5. The slurry of claim4, wherein the moisture barrier comprises alkyltene dimer (AKD) in therange of about 3.5%.
 6. The slurry of claim 5, wherein the oil barriercomprises a water based emulsion.
 7. The slurry of claim 6, wherein thewater based emulsion comprises fluorine containing a fluorocarbon resin.8. The slurry of claim 6, wherein the water based emulsion comprisesfluorine containing a fluorine polymer.
 9. The slurry of claim 2,wherein the retention aid comprises an organic compound in the range of0.1-1% of the slurry volume.
 10. The slurry of claim 1, wherein the pulpmixture comprises old corrugated containers (OCC) in the range of about70% and newsprint (NP) in the range of about 30%.
 11. The slurry ofclaim 1, wherein the rigidity component comprises a liquid starch. 12.The slurry of claim 11, wherein the rigidity component further comprisesa low charge liquid cationic starch.
 13. The slurry of claim 1, whereinthe fibers exhibit a freeness in the range of 100-700.
 14. The slurry ofclaim 1, further comprising a vapor barrier comprising a long chainfluorine-based polymer.
 15. The slurry of claim 14, wherein the vaporbarrier comprises in the range of about 0.1-3% of the slurry weight. 16.The slurry of claim 1, wherein the rigidity component comprises modifiedpolyamines configured to form both hydrogen and ionic bonds with thefibers.
 17. The slurry of claim 1, wherein the rigidity componentcomprises polyamide-epichlorohydrin (PAE) resin.
 18. A fiber-basedslurry for use in vacuum forming microwavable food trays, the slurrycomprising: a pulp mixture including at least one of old corrugatedcontainers (OCC) and newsprint (NP); a moisture barrier comprisingalkyltene dimer (AKD); an oil barrier comprising a water based fluorineemulsion; and a rigidity component comprising liquid starch.
 19. Theslurry of claim 18, further comprising: a vapor barrier comprising along chain fluorine-based polymer.